Flaw detecting apparatus



May 20, 1941. w. c. BARNES ETAL FLAW DETECTING APPARATUS Filed June 6,193a 3 Sheets-Sheet 1 May 20, 1941. w, c BARNES ETAL 2,242,220

FLAW DETECTING APPARATUS 3 Sheets-Sheet 2 Filed June 6, 1938 m mu cu cuF g Q her QM W @ww MW W HQ, M

y 1941- w. c. BARNES EI'AL 2,242,220

FLAW DETECTING APPARATUS Bel/1722s 3 Sheets-Sheet 3 inventors Q flWalerFiled June 6, 1938 'mi8ht be disadvantageous in it neverthelessincorporates Patented May 20, 1941 UNITED. STATES PATENT OFFICE amaze MWDETECTING APPARATUS Walter C. Borneo, Lake Blair, and Henry W. Kee'viLHighland Park, IlL

Application runes, 1m, Serial No. 212,119

22 Claims.

In testing rails for flaws by the residual magwhich a detector unit ispassed along a mangetized rail, the first step is to mm- For thispurpose the detector car carries-one or more electromagnets adapted tocause magnetic flux to pass through the rail. To cause a high proportionof the flux available from the coil to pass through the rail, it isdesirable to have one pole of the core closelyand uniformly associatedwiththe rail as by securing to the core a shoe which slides along therail. It is necessary, however, that the magnet and its associated partsbe well above the rail when not in use, and expensive and complicatedmechanisms have been employed heretofore for raising and holdingsuspended in inoperative position the relatively heavy correspondingarts of detector cars now in use and alternatively holding them in thedesired operative position with sufllcient rigidity and resiliency tokeep them in proper contact with the rail. .Not only is thisconstruction expensive if applied to a magnetic method of testing butthe inertia of the heavy coil structure its reaction to theirregularities of the rail surface. Without adequate means for absorbingthe shock as the magnet slid over a rail joint, crossing or the like,the shock might'injure the magnet or even be transmitted to the car.

According to the present invention both the objection to the expensiveraising and lowering mechanism and the dlfflculties in connection withabsorbing the shock are overcome by providing a rigidly mounted coil andcore with a relatively movable extension of the core which slides alongthe rail when in use but which moves with respect to the core to avoidtransmitting shock thereto and may be easily drawn upwardly when not inuse. Because of the light weight of the movable part and because itsinertia is relatively insignificant compared to its magnetic attractionfor the rail, a uniform position with respect to the rail may bemaintained and the raising and lowering mechanism may nevertheless bequite simple.

The mechanism provided in accordance with this invention is accordinglyquite simple but several special features. The cross-sectional area ofthe core extension is kept relatively large all the way from the core tothe rail so that there will not be any parts of the core which approachsaturation so closely as to in effect form a constriction that wouldblock off the flow of flux. Also, a linkage arrangement is providedwhich is relatively free from wear and which keeps the magnetic shoe ina position generally horizontal, though permitting slight variationstherefrom.

Additional advantages and objects of the invention will be apparent fromthe following description and from the drawings, in which:

Fig. 1 is a side view of a detector unit equipped with one embodiment ofthis invention.

Fig. 2 is a transverse sectional view taken approximately on the line2-4 of Fig. 1 and showing the rear view of the embodiment of thisinvention shown in Fig. 1.

Fig. 3 is a perspective exploded view of the movable pole constructionof Fig. 1.

Fig. 4 is a perspective view of the fixed pole of Fig. 1.

Fig. 5 is a fragmentary side view showing the movable pole in raisedposition.

Fig. 6 is a horizontal sectional view looking down on the operatingmechanism for the movable pole.

Fig. 7 is a front view showing particularly the movable mechanism.

Fig. 8 is a fragmentary side view partially broken away, showing variousdetails of the illustrated embodiment of this invention.

A preferred embodiment of this invention has been shown in the drawingsand will hereinafter be described all as required by section 4888 of theRevised Statutes, but the appended claims, which are required for thepurpose of pointing out the invention, are not to be limited by thisspecific disclosure except to the extent that may be required by theprior art.

One outstanding advantage of the method and apparatus of the system forwhich this invention is designed is that it may be embodied in a railcar of modest size, such for example as the car shown in Fig. l. The carcomprises a house body 20 mounted on an underframe II which in turn issupported on front and rear wheels 22 and 23, respectively. It is ofsome importance that the wheels be of magnetic material, as is usual.

The car is normally driven in the direction indicated by the arrow inFig. l with the driver sitting at 24 and the engineer in charge of testssitting at 25. Since the controls form no part of the present invention,none will be described.

The principle of flaw detection in accordance with which this inventionis used consists in introducing a strong magnetic flux into the rail orother magnetizable body to be tested, and after removing the energizingflux, then testing the body for traces of residual magnetism.

Each side of the car is equipped with a forward electromagnet 26 and arear electromagne-t 21, the former preferably being in advance of thewheel 22 and the latter preferably being intermediate the Wheels 22 and23. Following the wheel 23 is a detector generally designated 28, andsince the magnets 26 and 21, together with the detector 28 are identicalwith the corresponding magnets and detector on the other side of thecar, only one set will be described.

The magnets 26 and 21 are also identical, and the details of theirconstruction are shown in Figs. 2 to 8, inclusive. In explaining theirconstruction reference may be made to one of them only, as for examplethe magnet 26. This magnet comprises a coil 29 preferably made in twoparts to facilitate handling and replacement, and a core 30 which isprovided at its forward end with a retractible pole 3| in the form of ashoe which may be lifted from the position shown in Fig. 8 (the serviceposition) to the position shown in Fig. (light-running position).

The electromagnet is supported from the car underframe by non-magneticbars 32 preferably of stainless steel. The support bars 32 are securedto the horizontal portion 30 of the core by a plurality of bolts (Fig.8), those at the forward end of the core serving the additional functionof clamping pole plates 34 and 36 to the core. These two plates togetherwith links 36 and 31' and the magnet shoe 3| constitute an extension ofthe core, and all are made of annealed mild steel; or equivalentmagnetic material.

The forward ends of the plates 34 and 35 are held apart by a spacer 38through which bolts 39 pass so that an opening 40 is provided withinwhich the links 36 and 37 may operate. The links are pivotally connectedat their lower ends to the magnet shoe, as indicated at 4|, and each hasa slot 42 through which a guide bolt 43 passes. The upper ends of thelinks are connected by a clevis 44 and chain 45 to a bell crank lever 46pivoted at 47 to the front support bars 32 and operated by plunger 48 ofair cylinder 49. The lever 46 and the air cylinder parts are pref erablyall non-magnetic, such as bronze, with the exception of the spring 84which is of steel.

The magnet shoe is best shown in Fig. 3 and it comprises a block 50 ofmild steel, to the base of which a wear shoe or runner 5| ofnon-magnetic material, such a manganese or other wearresistant steel, issecured by clamping plates 52. The plates 52 are provided with a bevelededge 53 adapted to engage a similarly beveled edge 54 of the runner 5|,and a flange 55 provided along the upper margin of the plates 52 acts asa fulcrum about which the plates revolve when securing bolts 55 arescrewed into the block 58. Whenever a runner requires replacement due towear, it is only a matter of a few minutes to make the replacement dueto the ease with which the plates 52 may be removed from the block 50.

The magnet block 50 with its runner 5| is made sufficiently wide so thatit always maintains its proper position on the rail even when the car isrounding curves, or when there is lateral sway of the car. In normaloperation, the shoe 3| rides on the top surface of the rail andaccommodates itself to the unevenness in the rail surface. When the caris not being used for testing, but is traveling from one place to another at comparatively high speeds, the retractible shoe 3| is lifted tothe position shown in Fig. 5 by action of spring 84 upon releasing airfrom the air cylinder 49.

In practice, it has been found satisfactory to the electrical circuitenergize the coils 29 from 110 volt D. C. source of electromotive force,and to provide approximately 25,000 ampere turns on each electromagnet.The core 30 preferably has a cross-sectional area of approximately sixsquare inches, and the pole plates 34 and 35, links 36 and 3'! and shoe3| preferably have such shape and size that the energizing fluxtraveling through the iron circuit always has adequate crosssectionalarea through which .to pass. It should be understood, of course, thatthe mention of six square inches for the magnetic circuit is merelyillustrative and that the figure may vary as service conditions demand.Also, by way of illustration, the rear end of the core 38 may be spacedabove the top of the rail a distance of 5% inches and a. distance of 14%inches from the car underframe, these distances having been foundsatisfactory.

The support bars 32 are preferably carried on the car underframe byangle flanges 58 secured to cross members 59 extending betweenlongitudinal sills 60 of which there are two on each side of the car.

The detecting apparatus 28 used to indicate residual magnetism adjacentthe rails in the vicinity of flaws, together with its mounting and whichconnects it with the recording apparatus, is shown in Fig. 1, but sincenone of this apparatus is claimed per se in this application, thedescription of it will be limited to that which is necessary for showingthe operativeness and useful combination of detecting apparatus withmeans for setting up residual magnetism in the rail.

One or more detector coils, with their cores, are mounted in a box 69adjustably supported, both laterally and vertically from a detectorcarriage ll having front and rear runners l2 and 13, respectively, whichmay be of stainless steel. Springs 14 and 15, secured at one end to abracket 16, which projects downwardly from the car underframe outside ofthe gauge line of the track and at the other end to the detectorcarriage 1|, hold the carriage in proper lateral position with respectto the rail as determined by an elongated guide runner 11 secured to thecarriage.

The carriage 1| is moved from service position to light-running positionby cables 16 and 18 ,which pass over pulleys and are operated by asuitable air cylinder. The detector carriage is moved longitudinally ofthe rail by traction cables 8| which are firmly anchored to dependingbars 82.

The electrical circuits have not been illustrated and need not bedescribed, it being sufficient to state that a suitable amplifying andtranslating system is connected to each coil in the box 69 for recordingthe magnetic fields and for indicating on the rail the point at which aflaw has been detected.

From the foregoing the general operation of the testing equipment may beunderstood. First, the magnets 26 and 21 with their shoes 3| sliding onthe rail magnetize the rail. The. two magnets positioned on oppositesides of the wheel 22 seem to magnetize the rail more thoroughly thanone magnet would alone. Subsequently, the detector unit 28, which ispreferably positioned sufflciently far from the magnet 21 not to beinfluenced thereby directly, 18- tects any magnetic fields adjacent thetop of the rail head which may indicate flaws.

Inasmuch as the purpose of the detector unit I3 is to detect thepresence of external fields caused adjacent to flaws by the residualmagnetism of the rail. it is of course desirable that the rail be quitestrongly magnetized. So that the intensity of the field adJacent a flawwill indicate the nature of the flaw, it is desirable that themagnetization be relatively uniform. The movable pole constructionsincluding the shoes 3| is a very important feature in obtaining bothadequate and uniform magnetization of the rails.

In order to obtain maximum magnetizing effect from a given magnet 23 onepole of the magnet should extend quite close to the rail. Surprisingthough it may seem, it has been found that best results are obtained byleaving the other pole of the magnet a considerable distance above therail. The reason for this is that with the rear pole in contact with orclose to the rail some of the flux would pass away from that pole in thewrong direction in the rail and hence tend to de-magnetize the rail. Theshoe 6| serves the purp se of a pole constantly in magnetic proximity tothe rail. Because of its movability with respect to the rigidly mountedmagnet 33 it can follow any slight variations in the upper surface ofthe rail. In this connection it should be pointed out that itfollowssuch variations without any damage to the magnet 36. Any joltsadministered to the shoe 3| in crossing rail joints, for example, aretaken up with substantial completeness by pivoting of the links 36 and31. If it were attempted to mount the heavy coil 26 so that it, insteadof a movable pole portion thereon, would follow the slight variations ofthe rail, the inertia of this heavy coil might give considerable troublesince it might not rise and fall nearly as readily as does therelatively small shoe 3|. The shoe 3| needs no springs to force it intocontact with the rail since it is drawn into firm contact therewith bythe magnetic attraction between the shoe 3| and the rail. As a matter offact; this magnetic attraction is so great that there is considerablewear on the wear plate or runner For this reason the construction shownin Fig. 3, which permits the ready replacement of the runner 3|, is veryimportant. i

Although the clevis 44 may comprise two independent and pivotallyconnected clevises, one for each of the links 36 and 31, it is preferredthat it be a double clevis as seen best in Fig. 3. Such a' double clevismay be formed very simply by two V-shaped plates as shown. One advantageof the double clevis is that it maintains the links 36 and 31 spacedapart the same distance as are the guide or pivot pins 43 and 4| so thatthe wear on the pins 43 is reduced to a minimum. If the clevis 44 weremade of two separate portions pivoted to the chain 45, it would tend todraw the links 36 and 31 toward one another and make them rub withgreater force on the pivots 43. Besides increasing the wear, this wouldincrease the force required to raise the links 36 and 31 and the shoe3|. With the friction reduced by a rigid double clevis and because ofthe relatively small size of the shoe 3|, the air cylinder 43 may befairly small. This helps to make practical the provision of a separateair cylinder for each of the magnets. These air cylinders are veryeconomically operated partly because of their small size and partlybecause the spring 34 therein normally urges the plunger into thecylinder, raising the shoe 3| so that no air is required to hold theshoe up. Accordingly, air is only used to expel the plunger 43 inlowering the shoe 3| to the rail.

The air pressure need not be continued after the magnet is energizedsince the magnetic attraction will hold the shoe 3| down. In fact,spring 34 can be so designed as to Just support the shoe 3| andassociated parts when the magnet is de-energized, in which case theenergization of the magnet will pull the shoe 3| down and the aircylinder need not be provided at all.

Another advantage of the use of the rigid clevis or link 44 whichmaintains the links 36 and 31 properly spaced apart is that it preventsthe shoe 3| from being tilted very far away from'the horizontal. Ofcourse. a reasonable amount of freedom in its movement is desirable sothat it may conform to the irregularities of the rail, but the link 44does not interfere with this slight amount of freedom.

The mounting of the air cylinder 43 is very simple. Its base cap 33 iscast with an extension 31 thereon which is pivoted to two side plates 33secured to support bars 32. The lever 43 is also pivoted to these sideplates.

It should be noted that the shoe 3| always drags rearwardly with respectto the movement of the car. Thus, as illustrated in the drawings, whichassume the car to be moving forwardly, the shoe 3| drags toward the rearof the car. If, however, the car should be reversed, the slots 42 wouldpermit the links 36 and 31 to slide upwardly on pins 43 to permit theshoe 3| in effect to pass under the pins 43 and drag in the oppositedirection. This, together with the use of the heavy wear plate BI andthe heavy parts which are used throughout partly for the purpose ofproviding adequate cross section for the flow of flux, provides a verysturdy unit which will very rarely need any attention other than theoccasional replacement of the wear plate or runner 5|.

To minimize further the possibility of expensive repairs, the coils 23are preferably provided in two or more parts so that if one of them isfound to be defective or burns out it-may be replaced without having toreplace the other.

From the foregoing it is seen that a very satisfactory magnetconstructlon is provided for magnetizing rails while suspended from aflaw detector car. The main body of the magnet is rigidly supported bythe car while a relatively movable pole portion slides on the rail andforms an adequate magnetic path between the core and the rail. Themovable portion is constructed to move so easily that it may be raisedout of the service position to the light-running position simply byspring action with the result that a relatively small air cylinder maybe usedfor lowering it. Because of the reduction in friction the wear isnegligible throughout the magnet except for the readily replaceable wearplate which engages the rail. Because of the uniform spacing of themovable pole portion with the rail and because of the ease with whichthe shoe may follow the irregularities of the rail, the rail isefficiently and uniformly magnetized.

We claim:

1. Rail-magnetizing apparatus including a coil, a core within the coiland extending therefrom at one end, a link movable with respect to thecore but magnetically connected thereto, and means carried by the linkadapted to carry flux to the rail."

2. Rail-magnetizing apparatus including a coil, a magnetic core withinthe coil and having an extension beyond the core, a pair of magneticlinks pivoted to the extension one in front of the other, and a shoesimilarly pivoted to the links for engagement with the rail and movementwith respect to the core.

3. Rail-magnetizing apparatus including a coil, a magnetic core withinthe coil and having an extension beyond the core, pins on the extensionone in front of the other, a slotted magnetic link slidable on each pin,and a shoe pivoted to the links for engagement with the rail andmovement with respect to the core.

4. Rail-magnetizing apparatus including a coil, a magnetic core withinthe coil and having an extension beyond the core, a pin on theextension, a slotted magnetic link slidable on the pin, and a shoepivoted to the rail and movement with respect to the core.

5. Rail-magnetizing apparatus including a coil, a magnetic core withinthe coil and having an extension beyond the core, a pin on theextension, a slotted magnetic link slidable on the pin, and a shoepivoted to the link for engagement with the rail and movement withrespect to the core, said link being free to swing in either forward orbackward direction permitting the shoe to drag rearwardly with respectto both directions of movement of the core and coil,

6. Rail-magnetizing apparatus including coil, a magnetic core Within thecoil and having an extension beyond the core, a pin on the extension, aslotted magnetic link slidable on pin, a shoe pivoted to the link forengagement with the rail and movement with respect to the core, andmeans engaging the upper ends of the link and adapted to raise it toraise the shoe from the rail.

7.Rai1-magnetizing apparatus coil, a magnetic core within the coil andhaving an extension beyond the core, pins on the ex tension one in frontof the other, a slotted magnetic link slidable on each pin, a shoepivoted to the links for engagement with the rail and movement withrespect to the core, andmeans engaging the upper ends of the links andadapted to raise them to raise the shoe from the rail, the link-engagingmeans comprising a olds the upper ends thereof in a spaced relationshipcorresponding to the spacing of the pivots.

8. The combination of a rail car, a magnet rigidly secured thereto andincluding a core, a link magnetically connected to the core but movablewith respect thereto, and a shoe carried by the link and adapted toengage the rail, the shoe including a portion readily removable topermit replacement thereof.

9. The combination including and being of greater width than the railhead so as to maintain adequate contact therewith in spite of curves inthe rail.

10. Rail-magnetizing apparatus including a link for engagement with thethe rail.

links, and during operation resting on the end relative to the car tionto control its vertical position.

15. In combination, a rail means for raising and lowering the polepiece, including an air cylinder secured to the support members.

tion in which the car is moving when the pole piece is in contact withthe rail.

18. In combination with a rail car having a magnet mounted thereon, amovable pole piece Ior the magnet, means for raising and lowering thepole piece independently of the magnet with regard to contact with therail, and means for maintaining the pressure of the pole piece upon therail constant regardless of relative movement between the magnet and therail during car movement along the rail.

19. In combination a rail car, a magnet mounted upon the car and havingits core located at a fixed position on the car, a pole piece mounted onthe core and adapted to be raised and lowered independently of the coreand with respect to the rail, and means for supporting the pole piece aspaced distance from the rail when the pole piece is raised.

20. In combination with a rail car, a magnet mounted on the car with thecore supported a predetermined distance above the rail, a pole pieceassociated with the core and movable with respect to the core and therail, and means carried by the car for raising and lowering the polepiece independently of any movement of the magnet, and for supportingthe pole piece in raised position.

21. In combination with a rail car, a horizontal magnet mounted on thecar with the core supported a predetermined distance above the rail, apole piece associated with the core and movable with respect to the coreand the rail, means operable from inside the car for raising andlowering the pole piece independently of any movement of the magnet.

22. In combination with a rail car, a horizontal magnet rigidly securedto the car with the core thereof located a spaced distance from therail, a pole piece mounted on the core and extending therefrom towardsthe rail, said pole piece being movable with respect to the core and therail, and means for moving the pole piece towards and away from the railindependent of the magnet, said means including a device for supportingthe pole piece a spaced distance from the rail when the pole piece israised.

WALTER C. BARNES. HENRY W. KEEVIL.

